The object of this proposal is to elucidate the molecule mechanisms regulation transcription of the human neuronal nitric oxide synthase (NOS1) gene. This will be accomplished by identifying genetic elements that permit CNS expression of the human NOS1 gene; determining how transcriptional control is achieved vis a vis these elements; and creating transgenic mouse-based models to study human NOS1 promoter function in developing, regeneration, and traumatized neurons. NOS 1 mRNAs with different 5' terminal exons are transcribed in the CNS by separate promoters. Aim 1 proposes to examine the structure and distribution of these 5' terminal exons. Aim 2 proposes to identify cis acting elements essential for functioning of each promoter and to determine whether factors present in developing, regenerating, and/or traumatized neurons interact with these elements. Aim 3 proposes to determine whether the 4.3 kb human NOS1 promoter complex encodes sufficient information to direct appropriately regulated expression of law Z in olfactory receptor neurons, using previously constructed lines of transgenic mice. Aim 4 proposes to generate lines of law z-expression transgenic mice with longer fragments of the NOS1 gene, to determine whether cis-acting elements of the NOS1 gene can confer a spatial and temporal pattern of gene expression on the law Z reporter that reflects expression of endogenous NOS1 throughout the entire CNS during development and in response to neurotrauma. This research is important for several reasons. First, establishing the basic mechanisms that underpin NOS1 transcription in the CNS would mark an essential step toward developing a pharmacologic ability to regulate NOS1 mRNA, and consequently NOS 1 protein in the CNS. An avalanche of data point out physiological and pathophysiological roles of NOS in the CNS, suggesting that clinical treatments may emerge from such an ability. Second, the complex pattern of NOS1 gene expression, involving regionally specific prenatal and postnatal alterations, indicates that principles of general relevance to neuronal development are likely to be derived from studies of NOS1 transcription. Third, transcription of NOS1 in the CNS is controlled by two closely linked but separable promoters. Elucidation of the mechanisms by which this novel genomic structure regulates NOS1, gene expression should expand our general appreciation of how transcriptional control is achieved in the CNS.